> -----Original Message----- > From: Stuart Hayes [mailto:stuart.w.hayes@xxxxxxxxx] > Sent: Thursday, June 7, 2018 11:00 AM > To: Warzecha, Douglas > Cc: Limonciello, Mario; Dominguez, Jared; linux-kernel@xxxxxxxxxxxxxxx; platform- > driver-x86@xxxxxxxxxxxxxxx > Subject: [PATCH resend v2] dcdbas: Add support for WSMT ACPI table > > If the WSMT ACPI table is present and indicates that a fixed communication > buffer should be used, use the firmware-specified buffer instead of > allocating a buffer in memory for communications between the dcdbas driver > and firmare. > > Signed-off-by: Stuart Hayes <stuart.w.hayes@xxxxxxxxx> > Tested-by: Mario Limonciello <mario.limonciello@xxxxxxxx> > Acked-by: Doug Warzecha <douglas_warzecha@xxxxxxxx> > --- > v2 Bumped driver version to 5.6.0-3.3 > > > drivers/firmware/Kconfig | 2 +- > drivers/firmware/dcdbas.c | 102 > +++++++++++++++++++++++++++++++++++++++++++--- > drivers/firmware/dcdbas.h | 11 +++++ > 3 files changed, 109 insertions(+), 6 deletions(-) > > diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig > index b7c748248e53..a2bd6092bfa1 100644 > --- a/drivers/firmware/Kconfig > +++ b/drivers/firmware/Kconfig > @@ -125,7 +125,7 @@ config DELL_RBU > > config DCDBAS > tristate "Dell Systems Management Base Driver" > - depends on X86 > + depends on X86 && ACPI > help > The Dell Systems Management Base Driver provides a sysfs interface > for systems management software to perform System Management > diff --git a/drivers/firmware/dcdbas.c b/drivers/firmware/dcdbas.c > index 0bdea60c65dd..1699cfdcefe4 100644 > --- a/drivers/firmware/dcdbas.c > +++ b/drivers/firmware/dcdbas.c > @@ -36,12 +36,13 @@ > #include <linux/string.h> > #include <linux/types.h> > #include <linux/mutex.h> > +#include <linux/acpi.h> > #include <asm/io.h> > > #include "dcdbas.h" > > #define DRIVER_NAME "dcdbas" > -#define DRIVER_VERSION "5.6.0-3.2" > +#define DRIVER_VERSION "5.6.0-3.3" > #define DRIVER_DESCRIPTION "Dell Systems Management Base Driver" > > static struct platform_device *dcdbas_pdev; > @@ -49,19 +50,23 @@ static struct platform_device *dcdbas_pdev; > static u8 *smi_data_buf; > static dma_addr_t smi_data_buf_handle; > static unsigned long smi_data_buf_size; > +static unsigned long max_smi_data_buf_size = MAX_SMI_DATA_BUF_SIZE; > static u32 smi_data_buf_phys_addr; > static DEFINE_MUTEX(smi_data_lock); > +static u8 *eps_buffer; > > static unsigned int host_control_action; > static unsigned int host_control_smi_type; > static unsigned int host_control_on_shutdown; > > +static bool wsmt_enabled; > + > /** > * smi_data_buf_free: free SMI data buffer > */ > static void smi_data_buf_free(void) > { > - if (!smi_data_buf) > + if (!smi_data_buf || wsmt_enabled) > return; > > dev_dbg(&dcdbas_pdev->dev, "%s: phys: %x size: %lu\n", > @@ -86,7 +91,7 @@ static int smi_data_buf_realloc(unsigned long size) > if (smi_data_buf_size >= size) > return 0; > > - if (size > MAX_SMI_DATA_BUF_SIZE) > + if (size > max_smi_data_buf_size) > return -EINVAL; > > /* new buffer is needed */ > @@ -169,7 +174,7 @@ static ssize_t smi_data_write(struct file *filp, struct kobject > *kobj, > { > ssize_t ret; > > - if ((pos + count) > MAX_SMI_DATA_BUF_SIZE) > + if ((pos + count) > max_smi_data_buf_size) > return -EINVAL; > > mutex_lock(&smi_data_lock); > @@ -323,7 +328,8 @@ static ssize_t smi_request_store(struct device *dev, > break; > case 1: > /* Calling Interface SMI */ > - smi_cmd->ebx = (u32) virt_to_phys(smi_cmd->command_buffer); > + smi_cmd->ebx = smi_data_buf_phys_addr > + + offsetof(struct smi_cmd, command_buffer); > ret = dcdbas_smi_request(smi_cmd); > if (!ret) > ret = count; > @@ -482,6 +488,85 @@ static void dcdbas_host_control(void) > } > } > > +/* WSMT */ > + > +static u8 checksum(u8 *buffer, u8 length) > +{ > + u8 sum = 0; > + u8 *end = buffer + length; > + > + while (buffer < end) > + sum = (u8)(sum + *(buffer++)); > + return sum; > +} > + > +static inline struct smm_eps_table *check_eps_table(u8 *addr) > +{ > + struct smm_eps_table *eps = (struct smm_eps_table *)addr; > + > + if (strncmp(SMM_EPS_SIG, eps->smm_comm_buff_anchor, 4) != 0) > + return NULL; > + > + if (checksum(addr, eps->length) != 0) > + return NULL; > + > + return eps; > +} > + > +static int dcdbas_check_wsmt(void) > +{ > + struct acpi_table_wsmt *wsmt = NULL; > + struct smm_eps_table *eps = NULL; > + u8 *addr; > + > + acpi_get_table(ACPI_SIG_WSMT, 0, (struct acpi_table_header **)&wsmt); > + if (!wsmt) > + return 0; > + > + /* Check if WSMT ACPI table shows that protection is enabled */ > + if (!(wsmt->protection_flags & ACPI_WSMT_FIXED_COMM_BUFFERS) > + || !(wsmt->protection_flags > + & ACPI_WSMT_COMM_BUFFER_NESTED_PTR_PROTECTION)) > + return 0; > + > + /* Scan for EPS (entry point structure) */ > + for (addr = (u8 *)__va(0xf0000); > + addr < (u8 *)__va(0x100000 - sizeof(struct smm_eps_table)) && !eps; > + addr += 1) > + eps = check_eps_table(addr); > + > + if (!eps) { > + dev_dbg(&dcdbas_pdev->dev, "found WSMT, but no EPS > found\n"); > + return -ENODEV; > + } > + > + /* > + * Get physical address of buffer and map to virtual address. > + * Table gives size in 4K pages, regardless of actual system page size. > + */ > + if (eps->smm_comm_buff_addr + 8 > U32_MAX) { > + dev_warn(&dcdbas_pdev->dev, "found WSMT, but EPS buffer > address is above 4GB\n"); > + return -EINVAL; > + } > + eps_buffer = (u8 *)memremap(eps->smm_comm_buff_addr, > + eps->num_of_4k_pages * 4096, > MEMREMAP_WB); > + if (!eps_buffer) { > + dev_warn(&dcdbas_pdev->dev, "found WSMT, but failed to map > EPS buffer\n"); > + return -ENOMEM; > + } > + > + /* First 8 bytes of buffer is for semaphore */ > + smi_data_buf_phys_addr = (u32) eps->smm_comm_buff_addr + 8; > + smi_data_buf = eps_buffer + 8; > + smi_data_buf_size = (unsigned long) min(eps->num_of_4k_pages * 4096 - > 8, > + (u64) ULONG_MAX); > + max_smi_data_buf_size = smi_data_buf_size; > + wsmt_enabled = true; > + dev_info(&dcdbas_pdev->dev, > + "WSMT found, using firmware-provided SMI buffer.\n"); > + return 1; > +} > + > /** > * dcdbas_reboot_notify: handle reboot notification for host control > */ > @@ -548,6 +633,11 @@ static int dcdbas_probe(struct platform_device *dev) > > dcdbas_pdev = dev; > > + /* Check if ACPI WSMT table specifies protected SMI buffer address */ > + error = dcdbas_check_wsmt(); > + if (error < 0) > + return error; > + > /* > * BIOS SMI calls require buffer addresses be in 32-bit address space. > * This is done by setting the DMA mask below. > @@ -635,6 +725,8 @@ static void __exit dcdbas_exit(void) > */ > if (dcdbas_pdev) > smi_data_buf_free(); > + if (eps_buffer) > + memunmap(eps_buffer); > platform_device_unregister(dcdbas_pdev_reg); > platform_driver_unregister(&dcdbas_driver); > } > diff --git a/drivers/firmware/dcdbas.h b/drivers/firmware/dcdbas.h > index ca3cb0a54ab6..7ea5b3e070b9 100644 > --- a/drivers/firmware/dcdbas.h > +++ b/drivers/firmware/dcdbas.h > @@ -54,6 +54,8 @@ > > #define SMI_CMD_MAGIC (0x534D4931) > > +#define SMM_EPS_SIG "$SCB" > + > #define DCDBAS_DEV_ATTR_RW(_name) \ > DEVICE_ATTR(_name,0600,_name##_show,_name##_store); > > @@ -103,5 +105,14 @@ struct apm_cmd { > > int dcdbas_smi_request(struct smi_cmd *smi_cmd); > > +struct smm_eps_table { > + char smm_comm_buff_anchor[4]; > + u8 length; > + u8 checksum; > + u8 version; > + u64 smm_comm_buff_addr; > + u64 num_of_4k_pages; > +} __packed; > + > #endif /* _DCDBAS_H_ */ > > -- > 2.14.2 Darren, Andy, Stuart and I were hoping you guys could bring this through the platform-driver-x86 tree. The logic behind this is that the only consumer for dcdbas in kernel is dell-smbios. There isn't a subsystem maintainer for someone to pull in dcdbas even though the current maintainer (Doug W) has acked it. Thanks
